PATHOGENIC ORGANISM AND DISEASE TERMS

Pathogen microorganism that produces disease

A living organism of microscopic dimensions

Not all microorganisms are pathogens The microorganism in the pictures is not

a pathogen-does not produce a disease, in fact…

PATHOGENIC ORGANISM AND DISEASE TERMS

Disease deviation from normal

infectious disease noninfectious disease contagious (communicable) disease iatrogenic disease idiopathic disease

INFECTIOUS DISEASES

4 classes of agents (an agent is something that produces an effect) Bacterium/Bacteria Virus/Viruses Fungus/Fungi Parasites

BACTERIA

Is a living cell Prokaryote cell – No Nucleus Made up of cytoplasm, DNA, ribosomes,

flagella

BACTERIA Cocci _ round Staphylococci– round, clusters

Skin infections, wounds, food poisoning Gram positive

Streptococci- round, chains Strangles

Bacilli – rod shaped Anthrax

Endospore – oval body inside, resistant clostridium

Rickettsia –rod shaped, small ehrlichia

Spirochetes – spiral Leptospirosis

STAPHYLOCOCCI

Staphylococci- (cocci means round) – round, clusters

Skin infections, wounds, food poisoning MRSA Gram positive

Have thick wall that takes a stain (purple)

STREPTOCOCCI

Streptococci-round, chains Gram positive Strangles Pinkeye Strep throat Necrotizing fasciitis Sepsis

BACILLI

Bacilli – rod shaped Anthrax E. coli Salmonella Listeria Clostridium

E. COLI

Gram negative Anaerobic Lower intestines

CLOSTRIDIUM

Gram positive rod shaped bacteria Anaerobic (lives without oxygen) Food poisoning Clostridium perfringens enterotoxin

RICKETTSIA

Gram Negative bacteriaIntracellular parasites

•Typhus•Rocky Mountain Spotted Tick Fever

SPIROCHETTELyme diseaseLeptospirosis

1. EXAMPLES OF INFECTIOUS BACTERIAL DISEASES

Swine Yersinia

Cattle E Coli Mastitis Anthrax

Canine Leptospirosis (Lepto) Ehrlichiosis (Tick Fever) Bordatella

Bronchiseptica (kennel cough)

Rabbit Pasteurella (Snuffles) Tuleremia (vector-

ticks, flies) Horse

Tetanus Strangles

Cat Enteritis Cystitis

BACTERIA

Is a living cell Prokaryote cell – No Nucleus Made up of cytoplasm, DNA, ribosomes,

flagella

VIRUS Not a living cell!

But are considered alive because they reproduce, grow, develop, adapt, use energy sources from their environment

Made up of genetic material/ nucleic acid (DNA or RNA) enclosed in a protein shell

All sorts of shapes but are extremely tiny/ cannot see with a regular

microscope

Viruses insert their genetic material into a living cellThe cell becomes the virus’ host.

The virus DNA/RNA becomes a part of the cells DNA so that during cell division the virus is being replicated and passed on.

Eventually the virus’ DNA takes over, completely changes the host cell/ kills it’s host cell and continues to replicate and create lots more viruses

What about Retroviruses (Feline Leukemia and FIV) constantly change/ difficult to treat

VIRUS VS RETROVIRUS

Virus tends to contain DNA which can be replicated

Retrovirus contains RNA which must be transcripted (“converted”) into DNA. this process is not accurate “mistakes” are made in the

process DNA constantly varies because of

the mistakes Reason why retroviruses are

harder to treat/ prevent HIV, FIV, Feline Leukemia

2. EXAMPLES OF INFECTIOUS VIRUSES

Cattle Bovine Viral Diarrhea

(BVD)

Cats Feline Panleukopenia Calicivirus Feline Leukemia Virus Feline

Immunodeficiency Virus

Rabies - most warm blooded animals

Dogs Parvovirus Distemper

Horses West Nile Virus Equine Encephalomyelitis

Bacteria Virus

Ribosomes Present Absent

Living attributes

Living organism Opinions differ on whether viruses are a form of life or organic structures that interact with living organisms

Number of cells Unicellular; one cell No cells; not living

Structures DNA and RNA floating freely in cytoplasm. Has cell wall and cell membrane

DNA or RNA enclosed inside a coat of protein.

Treatment Antibiotics Vaccines prevent the spread and antiviral medications help to slow reproduction but can not stop it completely.

Enzymes: Yes Yes, in some

Nucleus No No

Virulence Yes Yes

Infection Localized Systemic

Benefits: Some bacteria are beneficial

Viruses are not beneficial.

Reproduction Fission- a form of asexual reproduction

Invades a host cell and takes over the cell causing it to make copies of the viral DNA/RNA. Destroys the host cell releasing new viruses.

Size Larger (1000nm) Smaller (20 - 400nm)

Cell wall Peptidoglycan/Lipopolysaccharide

No cell wall.Protein coat present instead

Comparison chart bacteria vs virus

PRIONS

Are proteins Not alive They do not have DNA or RNA They have an ability to reproduce Can cause inherited or transmissible

diseases

PRIONS

Prion diseases are fatal and cause progressive, neurodegenerative problems literally, holes in the brain The brain resembles a sponge / diseases are called

spongiform

Examples of spongiform encephalopathies are…. 1) Scrapie….in sheep and goats 2) BSE ….”Mad Cow Disease” 3) Chronic Wasting Disease…wild deer and elk

Transmitted by inherited disease, or ingested from tissue of infected animals (brain, spinal cord)

FUNGUS

Is a living cell… a “plant” type cell with a stronger protein

wall (chitin) Plants have a cellulose wall (a “sugar”)

Mold, yeast, mushroom Study of fungus is mycology Fungus “move” by growing

3. EXAMPLES OF INFECTIOUS FUNGI (MYCOSES)

Dermatophytes (Ringworm) Require keratin for growth

Thrush Coccidioidomycosis (Valley Fever)

Blastomycosis (South East) Histoplasmosis Candida (yeast infection)

BUDDING YEAST

VALLEY FEVER

Coccidioidomycosis (disease) Round fungus (Coccidioides Immitis)

Lives in the soil Dormant during dry spells Develops as a mold with long filaments that

break off into airborne spores when it rains The spores get into the air by disruption of

soil (construction, earthquakes, farming, dust storms)

4. EXAMPLES OF INFECTIOUS PARASITES Heartworm (Dirofilaria immitis) Trichinella…Trichinosis Hookworm (Ancylostoma), Whipworm

(Trichuris vulpis), Roundworm (Toxocara)

Giardia (protozoan) Coccidiosis (protozoan)

NONINFECTIOUS DISEASE CLASSIFICATIONS

Classifying diseases helps aid the veterinarian in obtaining a diagnosis

Helps the diagnostic process Clinical signs and symptoms could be the

result of several different disorders Differential diagnosis-a list of possible causes

of disease Rule Outs-ruling out possible causes of

disease through diagnostic testing, observation, trial treatment

Metabolic-disruption of normal chemical reactions Diabetes, hypothyroidism, hyperthyroidism, Cushings,

Addisons

Anomalies – Congenital Birth Defects Cleft palate, deaf, retinal dysplasia, dwarfism

Degenerative – progressive, permanent, longterm deterioration DJD (osteoarthritis), Bovine Spongioform Encephalopathy

(BSE)

Trauma – Traumatic reticuloperitonitis, high rise syndrome, sucking

chest wound, diaphragmatic hernia, peritonitis, prolapsed uterus

Toxins - ingestion, inhalation, contact Antifreeze, misapplication of flea and tick products, warfarin

(rat poison), toads,OTC medications, illegal drugs, plants

Immune Immune Mediated Hemolytic Anemia (IMHA), System Lupus

Erythematosus (SLE), Pruritis and Atopy (itchiness and hairloss) [allergies]

Iatrogenic- a condition that develops as a result of treatment Hyperadrenocorticism (Cushings)- can be caused by treatment

for a severe allergy problem Surgery-excision of Thyroid glad to treat hyperthyroidism in

cats…parathyroid may also be removed causing iatrogenic hypoparathyroidism.

Idiopathic- no explanation for underlying cause of the disease Idiopathic seizures Idiopathic renal hematuria

Neoplasm - benign or malignant tumor

Nutrition – Acute acidosis in ruminants, malnutrition, skeletal

disease, hypoglycemia, obesity, iodine deficiency

MADTIN T

Trauma Toxins

I Immune Iatrogenic idiopathic

N Neoplasm nutritional

M metabolic

A anomalie

D degenerative

NONINFECTIOUS DISEASE CLASSIFICATIONS

Metabolic-disruption of normal chemical reactions Diabetes, hypothyroidism, hyperthyroidism, Cushings, Addisons

Anomalies – Congenital Birth Defects Cleft palate, deaf, retinal dysplasia, dwarfism

Degenerative – progressive, permanent, longterm deterioration DJD (osteoarthritis), Bovine Spongioform Encephalopathy (BSE)

Trauma – Traumatic reticuloperitonitis, high rise syndrome, sucking chest

wound, diaphragmatic hernia, peritonitis, prolapsed uterus Toxins - ingestion, inhalation, contact

Antifreeze, misapplication of flea and tick products, warfarin (rat poison), toads,OTC medications, illegal drugs, plants

Immune Immune Mediated Hemolytic Anemia (IMHA), System Lupus

Erythematosus (SLE)Pruritis and Atopy (itchiness and hairloss) [allergies]

NONINFECTIOUS DISEASE CLASSIFICATIONS

Iatrogenic- a condition that develops as a result of treatment Hyperadrenocorticism (Cushings)- can be caused by treatment for a

severe allergy problem Surgery-excision of Thyroid glad to treat hyperthyroidism in cats…

parathyroid may also be removed causing iatrogenic hypoparathyroidism.

Idiopathic- no explanation for underlying cause of the disease Idiopathic seizures Idiopathic renal hematuria

Neoplasm - benign or malignant tumor Nutrition –

Acute acidosis in ruminants, malnutrition, skeletal disease, hypoglycemia, obesity, iodine deficiency

3 SEIZURE CASES

Seizure Case 1: A 3 month old male toy poodle. The dog is strictly a house dog and does not run free, In addition to the seizures, it has had intermittent diarrhea and is quite thin.

Differential Diagnosis (DfDx):Developmental Disorder- brain malformationHypoglycemia-could be secondary to poor diet, diarrhea,

intestinal parasitesHead Trauma- not likely with indoor dogToxins-potential for ingesting medications or illegal drugs,

chocolateInfectious causes of encephalitis- DistemperIdiopathic epilepsy-very unlikely due to age of dog

Seizure Case 2:A 2 ½ year old male golden retreiver. This dog is in excellent physical condition and has been eating well. This dog is free to roam the neighborhood and recently had one episode of vomiting and one episode where it was limping and stiff.

DfDx:Idiopathic epilepsy-this is high on the list because of age

and breed of dog at the onset of seizures.Head Trauma-the recent limping and stiffness raises this

possibilityToxins- the list is long, but possibilities include insecticides,

chocolateLiver Disease-definitely needs to be ruled out but dog has

been doing well otherwiseInfectious Encephalitis

Seizure Case 3:A 14 year old female schnauzer. This dog had its first seizure and since that time has not been acting normal. There has been some weight loss and a poor appetitie, and the owners feel the dog can no longer see. The dog is strictly an indoor dog with no history of trauma.

DfDx:Metabolic Disease-liver dx, hypogylcemia (insulinoma in the pancreas), DiabetesNeoplasia- the age of the dog, the blindness, lack of

normalcy after the seizure make this a high likelihoodIdeopathic epilepsy-very unlikely with the age of the animal